Chart-hub for recording instruments.



E. H. BRISTOL. CHART HUB FOR RECORDING INSTRUMENTS.

APPLICATION FILED JAN. 26, 1912.

Patented Dec. 31, 1912.

Invenior:

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UNITED STATES PATENT ornron.

EDGAB H. BRISTOL, FOXBORO, MASSACHUSETTS, ASSIGNOR TO THE INDUSTRIAL INSTRUMENT COMPANY, OF FOXBORO, MASSACHUSETTS, A CORPORATION OF CON- NECTICUT.

CHART-HUB FOR RECORDING INSTRUMENTS.

Specification of Letters Patent.

Patented Dec. 31, 1912.

To all whom it mag/concern:

Be it known that I, EDGAR H. Bnisron, a citizen of the United States, and a resident of Foxboro, in the county of Norfolk and State of Massachusetts, have invented an Improvement Instruments, of which the following ,description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

My invention relates to measuring and recording instruments, being more particularly concerned with the provision of improved means for fastening the recording chart to the shaft by means of which the chart is rotated during the making of the record thereon.

The invention will be best understood by reference to the following description when taken in connection with the accompanying illustration of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

, In the drawings: Figure 1 shows a front elevation of a recording instrument embodying my invention. Fig. 2 is a sectional view on line 2-2 of Fig. 1. Fig. 3 is a sectional view inplan taken on line 3-3 of Fig. 2, and Fig. 4 is a detail elevation of the chart hub with its shaft part-1y broken away.

Referring to the drawings and to the embodiment of my invention which I have there disclosed for illustrative purposes, I have there shown a recording instrument haying a casing 1 of any usual construct-ion, provided with a cover 2 having a glass 3 to protect the chart and the recording hand. A pivoted recording hand 4 is swung to and fro across the face of the chart by suitable means not shown and not forming an essential part of my present invention. This makes a record in the usual and wellknown manner, which it will be unnecessary to describe herein, upon the chart 5 which provided with suitable lines 6' representdivisions of time, and suitable lines 7 representing divisions of pressure or whateverother condition is desired to be reerde The chart 5. is placed upon the front face of a suitable platen 8 mounted within the casing 1 in any usual forming a backing or support for the chart while it is receiving its impression from the in Chart-Hubs for Recording or .desired manner and recording 'hand. This platen is as usual provided with fingers 9 extending a short distance onto the front face of the chart to keep it flat upon the platen while being rotated upon the latter. The chart is rotated by a shaft 10 having thereon a chart carrier comprising two clamping members ,11 and '12 having opposed clamping faces which abut respectively against the front and back surfaces of the chart.

The member 11 is provided with a boss 13 projecting through a central perforation 14 provided in the chart 5 and into a recess 15 provided in the member 12 and extending into the latter from the clamping face thereof. This boss is provided with a slightly tapered portion 16 which enters the perforation in the chart and accurately centers the latter. The member 12 is secured to the shaft 10 in any suitable manner, herein by providing said shaft with a shank 17 havingscrewthreaded engagement with said member and having a shoulder 18 against which the latter is firmly secured to prevent its rotation on the shaft, there being also provided a look-nut 19 to prevent r tation of the member 12 upon the screw-threaded shank of the shaft.

One importantfeature of my invention resides in the provision of the member 12 which preferably has no part whatever projecting through the perforation in the chart. On the contrary, however, when the member 11 is removed, the front end or clamping face of the member 12 lies substantially in the same plane as the front face of the platen 8, or in other words is flush therewith. This makes it possible to slide the chart into position across the face of the platen beneath the recording hand without materially disturbing the latter.

The members 11 and 12 are provided with suitable yielding means carried by one of these parts inter-engaging with the other to clamp the chart between the opposed clamping faces of the two members, and herein comprising one or more balls 20, herein three in number, located in suitable lateral pockets 21 provided in the member 12 and entering suitable lateraldepressions 22 provided in the hub 13. of the member 11. These balls are normally held in the depressions 22 by suitable yielding means herein a spring 23 of the helical type having its ends hooked together at 24. This spring engages all three of the balls and is located in a circumferential groove provided in the member 12 which groove serves to prevent the spring from slipping up or down on the latter. pressions 22 are of conical form and are so placed that the balls 20 engage the conical surfaces on the side nearest to the nearer end of the boss 13 as will be evident from inspection of Fig. 2. t will be obvious that the inward pressure of the balls on these inclined surfaces will tend to draw the member 11 inwardly with respect to the member 12 and accordingly the chart will be clamped between the clamping faces of the two members by sprin tension. This has the advantage of provi in uniform clamping action upon the cart as compared with the use of a screw for this purpose. I

Herein the member 11, which is the loose piece of the chart hub, is provided with a knurled head 26 by means of WlllCl'l it may be manipulated with the fingers. The member 1l may be removed by a forcible upward pull which will result in balls 20 being forced to recede into their respective pockets under the influence of the tapered surfaces of the depressions 22 in which said balls are normally located. When the loose piece is thus removed, the chart may be withdrawn from beneath the recording hand by a movement in the plane of the chart without disturbing the recording hand except to slightly lift its point from the surfac of the chart. The chart thus removed will be replaced by a new one by a simple reversal of the foregoing operation, and in putting the loose member 11 into place it should be given a rotating movement in addition to its inward'movement, in order to cause the balls to enter and seat themselves in their corresponding depressions as will be obvious. 7

One of the important features of my invcntion is in the placing of the chart centering device preferably upon the loose piece instead of upon the 'fixed piece of the hub, this construction being especially desirable because of the fact that it provides a flush surface across which the chart may be moved into position back of the recording end. This construction has also the further advantage of being quick and easy in operation as compared with the use of ascrew, and moreover has the further advantage over the use of the screw in that the chart is held by uniform pressure, whereas the screw either insecurely holds'the chart or else turns the latter from the position to which it has been adjusted with respect to the recording hand.

\ While I have herein shown and'described one form of my invention for illustrative Herein the defor a noeaeoe iur'poses, and have disclosed and discussed in detail the construction and arrangement incidental to one s ecilic application thereof, it is to be un erstood that the invention is limited neither to the more details or relative arrangement of parts nor to its specific application herein shown, but that extensive deviations from the illustrated form or embodiment of the invention may be made without departing from the principles thereof.

Having thus described my invention, what I claim is:

1. The combination of a chart provided with a perforation, a chart carrier comprising two parts one of which is provided with a recess and the other of which extends through said perforation into said recess, and yielding means carried by one of said parts and interengaging with the other, said yielding means comprising a rounded engaging member and a spring urging the latter into engagement with the other part.

2. A chart hub having, in combination, two parts having opposed clamping faces, one of said parts being provided ,with a recess extending thereinto from its clamping face, and the other of said parts extending into said recess, the recessed part heingpro vided with a lateral pocket, a member located in said pocket and interengaging with other part, and a spring to hold said member normally in such interengagement.

3. A chart hub having, in combination, two parts having opposed clamping faces, one of said parts being provided with a recess extending thereinto from its clamping face, and the other of said parts extending into said recess, the recessed part being provided with a lateral pocket and the other part being provided with a lateral depressioma member located in said pocket and entering said depression, and a spring to hold said member normally in said depression.

4. A chart hub having, in combination, two parts having opposed clamping faces, one of said parts being provided with a recess extending thereinto from its clamping face, and the other of said parts ex tending into said recess, the recessed part beingprovide'd with a lateral pocket and w the other part being provided with a lateral depression, a ball located in said pocket and entering said depression, and a spring to hold said ball normally insaid depression.

5. A chart hub having, in combination, two parts having opposed clamping faces,

.one of said parts being provided with a recess extending thereinto from its clamping face, and the other of said parts extending into said recess, the recessed part being provided with a plurality of lateral pockets, and the other part being provided with corresponding lateral depressions, a

plurality of balls loca-ted in said pockets,

two parts having opposite clamping faces,

one of said parts being provided with a reeessrxtending thereinto from its clamping face, and the other of said parts extending into said recess, the recessed part being provided with a plurality of lateral pockets, and the other part being provided with corresponding lateral depressions, a plurality of balls located in said pockets, respectively, and entering said depressions, and a circumferential spring engaging said balls and acting to hold the latter in said depressions.

7. A chart hub having, in combination,

two parts having opposed clamping faces, one of said parts being provided wit-h a recess extending therei-nto from its clamping face, and the other of said parts extending into said recess, the recessed part being provided with a plurality of lateral pockets, and the other part being provided with corresponding lateral depressions, a plurality of balls located in said pockets, respectively, and entering said depressions, and a circumferential spring engaging said balls and acting to hold the latter in said depressions, said recessed part being provided with a circumferential groove in which'said spring is located.

8. In a recording instrument, the combination of a chart, a platen against the front face of which said chart is disposed,

"and a clnlrt-earrier comprising an inner clamping member and an outer clamping member, the inner clamping member having its outer end substantially flush with the outer face of the platen and being provided with a recess extending inwardly from itssaid outer end, and the other member extending through the plane of the chart into.

said recess, said members having provision for clamping the chart therebetween.

9. The combination of a chart for a recording instrument, with interengaging chart holding devices, one of said devices engaging the other with a frictional grip whereby said devices may be separated by merely pulling them apart.

10. The combination of a chart for a recording instrument, with inter-engaging chart holding devices, one of said devices engaging the other with a frictional grip whereby said devices may be separated by merely pulling them apart, the rear device being flush with the plane of the chart.

11. The combination of a chart for a re- 

